The Concept Selection stage is not a FEED stage. Looking at the right perspective, Concept Selection is a precursor to FEED. The danger of not having the distinction of these stages during project implementation is the opportunity missed to consider other options as there is a focus on a selected few.
Concept selection should provide all the possibilities such as technical, environmental, delivery or economic are all considered for the project. Economic given the least consideration as the most economic at this stage is not necessarily the most economical considering the lifetime of the project.
It should be kept in mind that Concept Selection is concept selection and not FEED.